What are the causes of ataxia?

Causes of Ataxia

Ataxia results from a broad spectrum of etiologies that can be systematically categorized into structural, infectious/post-infectious, toxic-metabolic, autoimmune, genetic, and degenerative causes, with MRI brain being the preferred initial diagnostic modality for evaluation. 1, 2

Structural and Vascular Causes

• Posterior fossa masses including cerebellar tumors, Lhermitte-Duclos disease, and congenital malformations (Chiari I, cerebellar hypoplasias, rhombencephalosynapsis, Joubert syndrome) present with progressive ataxia and other posterior fossa symptoms 1
• Acute cerebellitis manifests with truncal ataxia, dysmetria, and headache; severe cases may progress to altered consciousness, increased intracranial pressure, hydrocephalus, and herniation 1
• Posterior circulation stroke affecting the cerebellum or brainstem causes acute-onset ataxia with associated neurological deficits 2
• Superficial siderosis presents with slowly progressive ataxia and hearing loss due to recurrent subarachnoid hemorrhage causing hemosiderin deposition on sub-pial brain and spinal cord layers 1
• Trauma-related ataxia accounts for approximately 5% of cases and requires evaluation for intracranial hemorrhage 2

Infectious and Post-Infectious Causes

• Post-infectious cerebellar ataxia is the most common cause of acute ataxia in children (33.6% of cases), typically developing within days to weeks after streptococcal or other infections 3, 2
• Bacterial cerebellitis may occur with cerebritis and meningitis, potentially resulting in late-stage cerebellar atrophy 1
• Whipple's disease, meningoencephalitis, and progressive multifocal leukoencephalopathy are treatable infectious causes requiring antibiotics and steroids 4

Toxic and Metabolic Causes

• Chronic ethanol abuse is a common cause of cerebellar atrophy and ataxia 1
• Methanol toxicity and heroin use can cause cerebellar damage, with opiate and solvent abuse leading to cerebellar atrophy and infarction 1
• Metronidazole-induced cerebellar toxicity shows increased T2 signal and reduced diffusivity in the dentate nuclei on MRI, with potential brainstem and corpus callosum involvement 1
• Mercury poisoning (Minamata disease) causes cortical or cerebellar lesions, atrophy, or peripheral neuropathy simulating ataxia 1
• Vitamin E deficiency results in cerebellar atrophy and ataxia 1
• Antiepileptics, anticancer drugs, insecticides, and heavy metals are potentially avoidable toxic causes 4
• Inborn errors of metabolism (intermittent maple syrup urine disease, pyruvate dehydrogenase deficiency, Hartnup disease) present with intermittent ataxia during stress or illness 5

Autoimmune and Paraneoplastic Causes

• Paraneoplastic cerebellar degeneration presents with subacute or acute onset of gait and limb ataxia, dysarthria, and ocular dysmetria 1
• Miller Fisher syndrome (Guillain-Barré variant) is characterized by the triad of ataxia, areflexia, and ophthalmoplegia 1
• Gluten ataxia responds to gluten-free diet, while other autoimmune ataxias (anti-GAD antibody-associated ataxia, steroid-responsive encephalopathy with autoimmune thyroiditis) require steroids, plasma exchange, or immunomodulation 4
• Demyelinating diseases including acute disseminated encephalomyelitis and multiple sclerosis can result in ataxia 1, 4
• Neuro-Behçet disease and other chronic vasculitides affecting the brain can lead to ataxia 1

Genetic and Hereditary Causes

• Autosomal dominant ataxias include spinocerebellar ataxias and episodic ataxia type 2 1, 5
• Autosomal recessive ataxias include Friedreich ataxia, ataxia-telangiectasia, ataxia with vitamin E deficiency, abetalipoproteinemia, cerebrotendinous xanthomatosis, Niemann-Pick disease type C, and coenzyme Q10 deficiency 1, 4
• X-linked disorders include fragile X-associated tremor/ataxia syndrome 1
• Other genetic syndromes with ataxia components include Christianson syndrome, neuro-ferritinopathy, and Huntington disease 1
• Mitochondrial disorders, neuronal ceroid lipofuscinosis, and GM2 gangliosidosis cause cerebellar atrophy in childhood 1

Episodic Ataxia Causes

• Genetic ion channel mutations are the primary cause of episodic ataxia 5
• Basilar migraines are diagnosed clinically with normal neuroimaging 5
• Benign paroxysmal vertigo and childhood benign paroxysmal ataxia show normal neuroimaging and vestibular testing 5

Critical Clinical Pitfall

Do not delay imaging in acute ataxia presentations—brain tumors account for 11.2% of acute ataxia cases in children and require immediate neurosurgical intervention, while acute cerebellitis can rapidly progress to herniation 2. MRI brain without and with contrast is the preferred initial test, though CT may be necessary when MRI is unavailable or trauma with hemorrhage is suspected 1, 2.